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氡222是铀238的气态子元素。通过地下水的流动、扩散和气压变化,氡可从其生成点迁移达数时至数百尺。本文描述美国西部普查砂岩型铀矿床的三个野外实例,其结果是很不相同的。科罗拉多州丹佛盆地的道逊建造属于下第三纪。在厚层的河成砂岩中,发现了大面积的氡异常,其强度达39脉冲/秒(本底值的8倍)。同时还有地下水中的铀异常。在射气异常峰值之下10—30尺处揭露了含铀砂岩层。在丹佛盆地的铀矿化上部,氡异常浓度值同铀矿化埋深成反比。在犹他州里斯本谷地琴尔建造(三叠纪)的莫斯贝克含矿砂岩组上,沿剖面测量了大气和土壤气体中的氡浓度变化。矿化产于方解石胶结的砂岩中,埋深19—2600尺。砂岩同页岩和泥岩成互层。上复的无裂隙页岩以及其斯贝克含矿砂岩的胶结物,是阻碍氡逸出和迁移的二个主要因素。它们还可能对氡起导向作用。因此,在里斯本谷地,用土壤气体的氡测量法无法探测深部的铀矿化。拉拉米盆地的温德河地层(下始新统)的射气测量给出了重复性良好的氡异常带,其数值达32脉冲/秒,而背景值为3—8脉冲/秒。土壤气体中的氡同该地区土壤中的铀有着明显的相关关系。射气异常的钻探结果表明,既无放射性异常,也无含矿砂岩。这些不同的结果说明,尽管氡是唯一的短寿命气体子元素,它的测量结果同其他地球化学方法一样,也是多解的。
Radon 222 is a gaseous sub-element of uranium 238. Through the flow of groundwater, diffusion and pressure changes, radon can migrate up to hundreds of feet from its generation point. This article describes three field examples of census sandstone-type uranium deposits in the western United States. The results are very different. The Dawson Formation in the Denver Basin of Colorado belongs to the Lower Tertiary. In thick bedded sandstone, a large area of radon anomaly was found with an intensity of 39 pulses / second (eight times the background value). There are also groundwater uranium anomalies. Uranium bearing sandstone layers were exposed at 10-30 feet below the peak of abnormal gas anomalies. In the upper part of the uranium mineralization in the Denver Basin, the anomalous concentration of radon is inversely proportional to the depth of uranium mineralization. Changes in radon concentration in the atmosphere and in soil gases were measured along the section at the Mossbacher-bearing sandstone group constructed in the Decal in the Lisbon Valley, in the state of Utah. Mineralization in the calcite cemented sandstone, depth 19-2600 feet. Sandstone interbeds with shale and mudstone. Uplift of the fissure-free shale and its Sbeike ore-bearing cements are two major obstacles to escape and migration of radon. They may also play a leading role in radon. As a result, deep soil uranium mineralization can not be detected using the radon measurement of soil gas in the Lisbon Valley. Radiometric measurements of the Wind River strata (Lower Eocene) in the Lamyam Basin give a well-replicated radon anomaly with a value of 32 pulses / second and a background value of 3-8 pulses / second. There is a clear correlation between radon in soil gas and uranium in the soil in the area. Abnormal gas drilling results show that there is neither radioactive nor ore-bearing sandstones. These different results show that although radon is the only short-lived gas subelement, its measurement is multifractal as other geochemical methods.